In terms of substitution effects, the major difference between our estimates and those from the US is that our data indicate that diet soft drinks are a substitute for sugar sweetened drinks, whereas US data suggest that diet soft drinks are a complement (as the price of sugar sweetened drinks goes up,
consumption of diet drinks goes down).18 22 This may explain
why a US
tax on sugar sweetened drinks has been so heavily resisted, as a «double whammy» on sales of both diet soft drinks and sugar sweetened drinks would occur.18.
My understanding of
why some say it doesn't is the argument that a
tax cut is more effective if it benefits the poor / middle class because the poor / middle class will spend most of it on
consumption (say groceries) rather than investment (say purchasing an extra rental property).